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Four Expert Issues From Trial

In Sit v. Trillium Health Centre, 2020 ONSC 2458, Justice Trimble addressed several issues related to expert evidence at trials.

Expert Report as an Aide Memoire

Justice Trimble confirmed that, unless a medical report is tendered as a medical expert’s evidence-in-chief in place of oral testimony, the report has no evidentiary value. The only admissible evidence is the expert’s oral evidence.

If a report is submitted at trial, it is only an aide memoire to the trial judge to permit him or her to follow and remember the evidence. The report is not in addition to the expert’s evidence in the witness box.

Inconsistencies Between Expert’s Report and Oral Evidence

Inconsistencies between the oral evidence of an expert witness and his or her written report are the proper subject of cross-examination.

However, if the expert witness was not cross-examined on an inconsistency between his or her oral evidence and the contents of the report, it is not open to a trial judge to place any weight on this perceived inconsistency in assessing the expert’s credibility.

Therefore, counsel must specifically cross-examine an expert on apparent inconsistencies between the expert’s oral evidence and his or her report. Counsel cannot refer to inconsistencies in closing argument without confronting the expert on the issue. This is a matter of trial fairness.

Reliance on Texts and Journals

Justice Trimble addressed an expert’s reliance on learned texts and treatises. His Honour noted that such documents are classic hearsay and, as such, are inadmissible. However, they are touchstones by which one measures the expert’s opinion.

Incorporating references from an article or treatise into an expert’s evidence does not relieve the expert from the obligation of actually expressing the view in the report or in his or her evidence.

By referring to and adopting a portion of a text or article, that portion of the text or article becomes part of the expert’s opinion evidence. The expert does not incorporate, by reference, the entire publication into the report.

Evaluating Evidence of Competing Experts

Justice Trimble outlined the following three-step process to evaluate the evidence of competing experts and to decide which expert’s opinion to accept:

  1. Qualifications and Impartiality – at this stage, the court should consider the qualifications of each expert witness, examine the experts’ training and experience, and consider their level of competence in the field in which they were qualified to give an opinion. The court must also consider whether the expert was impartial, or whether he or she appeared to unreasonably favour the party who called him or her as a witness. An expert’s lack of independence and impartiality goes not only to the admissibility of the expert’s evidence, but also to the weight to be given to that evidence once it is admitted.
  2. Assessment of Evidentiary Basis for the Opinion – at this stage, the court must examine the facts and assumptions upon which the expert relied on to form their opinion.
  3. Examining the Whole of the Opinion – at this stage, the court must examine and evaluate the opinion itself, as a whole. Did the expert consider all relevant information and give it appropriate emphasis in reaching the conclusion?

Justice Trimble indicated that, in assessing the weight of competing experts’ opinions, the court must accept or reject an expert’s opinion on a given issue as a whole.

His Honour said that the court is not entitled to pick and choose among various aspects and portions of the expert’s opinion on a given issue and fashion a new opinion from those aspects or portions that the court prefers from each experts’ opinion.

Justice Trimble stated that the court generally does not have the expertise to determine whether the expert is right or wrong in their opinion. If the court does this, it would, in effect, assume the role of the expert.